The Drug Enforcement Administration's war on marijuana has been losing ground recently as the agency's historical allies such as the White House, Congress and the Department of Justice begin to shift its positions on what the DEA considers is a dangerous drug.

Earlier this year, the DEA came under fire from an unlikely bipartisan alliance in both the Senate and House, following the administration's bust of industrial hemp seeds that were headed to research facilities in Kentucky, The Los Angeles Times reported

A measure was passed in the Republican-controlled House that prohibits federal agents from cracking down on medical marijuana operations and was supported by members of the Senate on both sides of the aisle.

Bill Piper, a Drug Policy Alliance lobbyist, said the tides are changing for marijuana policies as lawmakers have begun questioning the DEA's efforts on the matter.

"For 13 of the 14 years I have worked on this issue, when the DEA came to a hearing, committee members jumped over themselves to cheerlead," Piper said. "Now the lawmakers are not just asking tough questions, but also getting aggressive with their arguments."

According to The Los Angeles Times, Polis and Leonhart were at odds regarding the DEA's classification that marijuana remain a Schedule I drug, meaning it is among some of the most dangerous drugs out there.

"She has repeatedly embarrassed her agency before this body," Polis said.

Although Leonhart faces some tough critics and has been called to resign by more than 42,400 people in a signed petition, Rep. Frank Wolf, R-Va., came to her defense after Attorney General Eric Holder advised her to stop contradicting the president's administration.

Wolf called Holder's admonishment a "Nixonian effort to pressure a career law enforcement leader into changing her congressional testimony."

"[Leonhart] has done an outstanding job leading this agency during a challenging time," Wolf wrote to Holder.

The DEA head, who served as acting DEA chief during George W. Bush's administration, has staunchly opposed legalizing marijuana or lifting marijuana policies.

Her efforts have garnered the support from law enforcement agents who have spent most of their lives enforcing marijuana laws, said Sam Kamin, a University of Denver law professor.

"The Obama administration has to walk this tightrope. The youth vote and a number of populous states are moving in one direction, and elements of law enforcement are not," Kamin said. "To say (law enforcement is) going to let the states decide what federal law is, is difficult for them to swallow."